The present invention relates generally to wide band communication systems, and more particularly to interference avoidance in a wide band communication systems.
Wide band communication systems are useful in that they allow data to be transferred over a range of frequencies, potentially increasing data throughput as well as potentially increasing robustness of communications. Wide band communication systems and particularly ultrawideband communication systems, may use, for example, orthogonal frequency division multiplexing (OFDM) for transmission of symbols over a range of frequencies, often referred to as subcarriers. Ultrawideband systems may further increase the frequencies at which data is transmitted, for example by periodically switching, sometimes referred to as hopping, between different bands of frequencies. Using different frequency hopping patterns, often indicated by a time frequency code, a number of transmitter receiver pairs may utilize the same bandwidth simultaneously.
A disadvantage of the use of widebands of frequency for communications is that portions of the bandwidth may already be reserved for utilization by other communication systems. These other communication systems may interfere with the wideband transmissions and the wideband transmissions may interfere with transmissions of the other communication systems. As a practical matter, the other communication systems often have prior rights to the particular frequencies which they use, and ultrawideband transmitters may be required to not interfere with communications by others over those frequencies.
Avoiding interfering with other communication systems may be problematic at times. For example, different locations may have different reserved frequency bands. Moreover, the reserved frequency bands may not be in use in all places or at all times. Thus, in many instances it may be that for a large majority of the time communication over those reserved frequencies may be properly accomplished by UWB transmitters, allowing for increased bandwidth, so long as those UWB transmitters may avoid interference when those frequency bands are in use by the other communications systems.